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<title>The NEITHER Theory Revision System </title>

<h1>NEITHER</h1> <br> 

NEITHER is a propositional theory refinement system that will modify a
incomplete or incorrect rule base so as to make it consistent with a
set of input training examples.  NEITHER has been extended to revise
both Horn clauses and M-of-N rules.  An iterative greedy method is
used to efficiently compute repairs. <p>

NEITHER has also been used as part of separate system, ASSERT, which
performs student modeling.  ASSERT (Acquiring Stereotypical Student
Errors using Refinement of Theories) is an intelligent tutoring system
which inputs a knowledge base describing a domain and a set of student
errors on that domain and outputs a tutoring program tailored to fit
student needs.  Student behavior on the domain is modeled by
collecting any refinements to the knowledge base (made by NEITHER)
that were necessary to account for the student's behavior.  These
models are then used to generated feedback which should help raise
student peformance on that domain. <p>

The complete NEITHER Software System is available via 
<!WA0><!WA0><a href="ftp://ftp.cs.utexas.edu/pub/mooney/neither">anonymous ftp</a>.
This software contains the following items: <p> 

<ol> 
<li> The ASSERT Tutoring System 
<li> The CPP System - The specifics of a C++ Tutorial 
<li> The NEITHER System 
<li> PFOIL - a propositional FOIL induction system
<li> A system introduction and breakdown, including compilation 
instructions and execution traces.
</ol>

A more detailed description of this system can be found in the
following publications: <p>
<ol>
<li>Paul Baffes, "Automatic Student Modeling and Bug Library 
  Construction using Theory Refinement," Ph.D. Thesis, Department
  of Computer Sciences, University of Texas at Austin, December, 1994.
<li>Paul Baffes and Raymond Mooney, "Extending Theory Refinement to 
  M-of-N Rules," <cite>Informatica</cite>, 17 (1993), pp. 387-397.
</ol>


Poniters to these and other related papers can be found on our <!WA1><!WA1><a
href="http://www.cs.utexas.edu/users/ml/theory-rev.html">Theory Refinement</a> research page.<p>

<hr>
<address><!WA2><!WA2><a href="http://www.cs.utexas.edu/users/estlin/">estlin@cs.utexas.edu</a></address>
